In recent years, fiber laser devices have been used in processing machines for performing processing with laser light, medical devices such as surgical knives using laser light, and the like. In a fiber laser device, laser light generated from a laser oscillator and pumping light are input to an amplification optical fiber, and the amplified laser light is output from an output unit.
In such a fiber laser device, a certain period of time is required for the intensity of laser light to be stabilized from when the laser light is started to be output from the fiber laser device. That is, a certain period of time is required for laser light to rise.
As the rise time of laser light becomes shorter, the work efficiency becomes higher. Patent Document 1 listed below discloses a fiber laser device that requires a short period of time to stabilize the intensity of laser light.
In the fiber laser device disclosed in Patent Document 1 listed below, pumping light with a low and constant intensity is input to an amplification optical fiber during a period before laser light is output from the fiber laser device (a standby period), and a rare-earth element doped in the amplification optical fiber is pumped. That is, pre-pumping is performed before laser light is output. When laser light is output from the fiber laser device, seed laser light and pumping light with a high intensity are input to the amplification optical fiber, and amplified laser light is output. In this manner, before laser light is output from the fiber laser device, the rare-earth element in the amplification optical fiber is pumped by pre-pumping. Accordingly, the rise time of the laser light output from the fiber laser device is short (Patent Document 1).